refactor(scenario): remove step type and simplify scheduler to exec-only

- remove StepType, type column, and type field from step entity and DTOs
- remove executeLoginStep, executeSignStep, executeExecStep from scheduler
- inline exec logic directly in executeStepRun; all steps run execCode
- remove AuthService, EnvironmentService, runEnvironments from scheduler
- remove type selector from CreateStepPage and EditStepPage
- remove type badge column from ScenarioDetailPage
- fix useEffect dependency arrays in RunDetailPage (FINAL, id, runId, polling)
- fix duplicate /snippets proxy key in vite.config.ts
- remove unused escapeHtml export from hljs.ts

client/src/ui/CodeEditor/CodeEditor.tsx

@@ -12,13 +12,13 @@ export interface CodeEditorProps {
 
 function useMonacoTheme() {
   const [theme, setTheme] = useState(() =>
-    document.documentElement.getAttribute('data-theme') === 'dark' ? 'vs-dark' : 'vs-light'
+    document.documentElement.getAttribute('data-theme') === 'dark' ? 'vs-dark' : 'vs-light',
   );
 
   useEffect(() => {
     const observer = new MutationObserver(() => {
       setTheme(
-        document.documentElement.getAttribute('data-theme') === 'dark' ? 'vs-dark' : 'vs-light'
+        document.documentElement.getAttribute('data-theme') === 'dark' ? 'vs-dark' : 'vs-light',
       );
     });
     observer.observe(document.documentElement, {
@@ -49,11 +49,7 @@ export function CodeEditor({
 
   return (
     <div
-      className={[
-        styles.wrapper,
-        focused ? styles.focused : '',
-        error ? styles.hasError : '',
-      ]
+      className={[styles.wrapper, focused ? styles.focused : '', error ? styles.hasError : '']
         .filter(Boolean)
         .join(' ')}
       style={{ height }}